Hennessey Performance Engineering has created an HPE650 package for the Jeep Grand Cherokee SRT fitted with the 6.4-liter Hemi engine. When it leaves the showroom floor it has 470 horsepower and gets from 0-60 miles per hour in 4.8 seconds. When it leaves Hennessey's garage floor after the upgrade it has 650 horsepower – 530 hp at the wheels, according to Hennessey – and gets to 60 mph in 3.9 seconds on its way to running the quarter-mile in 12.6 seconds.